<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>WebSocket HelloWorld</title>
</head>
<body>

<input id="text" type="text"/>
<button onclick="send()">Send</button>
<button onclick="closeWebSocket()">Close</button>
<div id="message"></div>

<script>
    var ws = null;
    // 建立连接
    if ('WebSocket' in window) {
        ws = new WebSocket("ws://localhost:8080/ws");
    } else if ('MozWebSocket' in window) {
        ws = new MozWebSocket("ws://localhost:8080/ws");
    } else {
        alert('您的浏览器不支持WebSocket，请更换浏览器');
    }

    //连接发生错误的回调方法
    webSocket.onerror = function(){
        setMessageInnerHTML("error");
    };

    //连接成功建立的回调方法
    webSocket.onopen = function(){
        setMessageInnerHTML("open");
    };

    //接收到消息的回调方法
    webSocket.onmessage = function(event){
        setMessageInnerHTML(event.data);
    };

    //连接关闭的回调方法
    webSocket.onclose = function(){
        setMessageInnerHTML("close");
    };

    //监听窗口关闭事件，当窗口关闭时，主动去关闭webSocket连接，防止连接还没断开就关闭窗口，server端会抛异常。
    window.onbeforeunload = function(){
        ws.close();
    };

    //将消息显示在网页上
    function setMessageInnerHTML(innerHTML) {
        document.getElementById('message').innerHTML = innerHTML + '<br/>';
    }

    //关闭连接
    function closeWebSocket(){
        ws.close();
    }

    //发送消息
    function send(){
        let message = document.getElementById('text').value;
        ws.send(message);
    }
</script>
</body>
</html>